JP2000236362A - Circuit and method for detecting carrier frequency and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and highly accurately detect the frequency of a carrier wave contained in a modulated wave. SOLUTION: A modulated wave is converted to the modulated wave of a frequency component through an FFT processing part 401 and an amplitude calculating part 402 and recorded in an amplitude value memory 403. While controlling a central frequency setting circuit 404, a control circuit 410 sets a frequency (central frequency) for measuring symmetry in the modulated wave of the frequency component out of a frequency area estimated to contain the frequency of the carrier wave and sets plural pairs of two frequencies separated higher and lower than the central frequency respectively just for the same value. The control circuit 401 reads amplitude values corresponding to respective set pairs of two frequencies out of the amplitude value memory 403, mutually multiplies them and adds the result of multiplying each pair of two frequencies for each central frequency. By comparing the added results, the central frequency of the maximum added result is defined as a carrier frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection circuit for detecting a frequency of a carrier wave included in a modulated wave, a detection method, and a recording medium.

[0002]

2. Description of the Related Art Conventionally, in communication technologies such as wireless communication,
A method of extracting data (signal) by, for example, removing a carrier from a modulated wave has been adopted, and detecting the frequency of the carrier to be removed has become an important issue.

[0003]

However, in this method, when the maximum level (amplitude value) of a carrier to be detected is lower than the level (amplitude value) of data or noise, the carrier is detected with high accuracy. Was sometimes difficult.

[0004] The present invention has been made in view of the above situation, and facilitates the frequency of a carrier wave included in a modulated wave, and
An object of the present invention is to provide a detection circuit, a detection method, and a recording medium capable of detecting with high accuracy.

[0005]

To achieve the above object, a carrier frequency detecting circuit according to a first aspect of the present invention converts a modulated modulated wave from a time component signal to a frequency component signal. A carrier frequency detection circuit for detecting a carrier frequency from a modulated wave of the converted frequency component, a frequency component predicted to include the frequency of the carrier to be detected, a prediction predicted to be the frequency of the carrier Predictive frequency setting means for setting a plurality of frequencies; and two sets of the same frequency which are separated by the same value in directions larger and smaller than the predicted frequency set by the predictive frequency setting means.
Separation frequency setting means for setting a plurality of sets of separation frequencies, and two sets of each set by the separation frequency setting means.
Predicted frequency detecting means for detecting a predicted frequency such that the amplitude values of the modulated waves at the two separated frequencies are substantially equal,
Wherein the predicted frequency detected by the predicted frequency detection means is set as the frequency of the carrier to be detected.

According to this configuration, the characteristic of the modulated wave of the frequency component, that is, the amplitude value of the modulated wave of the two frequencies separated by the same value in the large direction and the small direction with the carrier frequency as the center is substantially the same. Using the equality, the frequency of the carrier is determined. For this reason, even when the level of the carrier is lower than the level of data, noise, or the like, the frequency of the carrier can be easily obtained with high accuracy.

The predicted frequency detecting means is set by the predicted frequency setting means and a multiplying means for multiplying the amplitude values of the modulated waves of the two separated frequencies by each set set by the separated frequency setting means. For each predicted frequency
Adding means for adding the multiplication results of the amplitude values of the modulated waves of the two separated frequencies of each set set by the separation frequency setting means; and comparing the addition results added by the addition means, and determining that the addition result is the maximum. Carrier frequency determining means for outputting the predicted frequency as a carrier frequency.

The predictive frequency setting means sets the predictive frequency in a range including a frequency having substantially the maximum amplitude value of the upper first wave and the lower first wave of the modulated wave of the frequency component. It is desirable to do.

The maximum value of the difference between the two separation frequencies set by the separation frequency setting means is set to about four times the number of the minimum unit data transmitted per unit time of the modulated wave. It is desirable to have been.

A receiving means for receiving the modulated wave; a means for detecting the modulated wave received by the receiving means to obtain an in-phase component and a quadrature component of a baseband; Means for converting a signal from a signal in the time domain into a signal of an in-phase component and a quadrature component in the frequency domain, and a square root of a sum of a square of the signal of the in-phase component in the frequency domain and a square of the signal of the quadrature component in the frequency domain. Means for obtaining a modulated wave of a frequency component.

A carrier frequency detecting circuit according to a second aspect of the present invention is a carrier frequency detecting circuit for detecting a carrier frequency of a signal including a carrier, wherein the carrier frequency detecting circuit detects a plurality of predicted frequencies which are predicted to be carrier frequencies. For each set prediction frequency, the same value is separated in the direction larger and smaller than the prediction frequency by the same value.
Separation frequency setting means for setting a set of two separation frequencies;
The amplitude of the signal at the separation frequency set by the separation frequency setting means is determined, and the carrier frequency is set to a predicted frequency at which the amplitude of the signal is substantially equal at the set separation frequency. Frequency detection means,
It is characterized by having.

According to this structure, the amplitude of the modulated waves of two frequencies separated by the same value in the large direction and the small direction with the carrier frequency of the modulated wave as the center becomes substantially equal. Is used to determine the frequency of the carrier. For this reason, even when the level of the carrier is lower than the level of data, noise, or the like, the frequency of the carrier can be easily obtained with high accuracy.

A method of detecting a carrier frequency according to a third aspect of the present invention is a method of converting a modulated wave from a time component signal to a frequency component signal, and detecting a carrier frequency from the converted frequency component modulated wave. In the frequency component predicted to include the frequency of the carrier to be detected, a predicted frequency setting step of setting a plurality of predicted frequencies predicted to be the frequency of the carrier, the setting in the predicted frequency setting step A separation frequency setting step of setting a plurality of sets of two separation frequencies separated by the same value in each of a direction larger than the predicted frequency and a direction smaller than the predicted frequency;
A predicted frequency detecting step of detecting a predicted frequency such that the amplitude values of the modulated waves of the two separated frequencies of each set set in the separated frequency setting step are substantially equal to each other, The detected predicted frequency is set as a frequency of a carrier to be detected.

According to this configuration, the characteristic of the modulated wave of the frequency component, that is, the amplitude value of the modulated wave of the two frequencies separated by the same value in the large direction and the small direction with the carrier frequency as the center is substantially equal to each other. Using the equality, the frequency of the carrier is determined. For this reason, even when the level of the carrier is lower than the level of data, noise, or the like, the frequency of the carrier can be easily obtained with high accuracy.

[0015] The predicted frequency detecting step includes a multiplying step of multiplying each pair set in the separated frequency setting step by an amplitude value of a modulated wave of two separated frequencies, and a prediction set in the predicted frequency setting step. For each frequency, an addition step of adding the multiplication result of the amplitude values of the modulated waves of the two separation frequencies of each set set in the separation frequency setting step, and comparing the addition result added in the addition step, A carrier frequency determining step of outputting the predicted frequency having the maximum value as the carrier frequency.

The predicted frequency set in the predicted frequency setting step is set within a range including a frequency at which the upper first wave and the lower first wave of the modulated wave of the frequency component have substantially the maximum amplitude value. It is desirable to be done.

The maximum value of the difference between the two separation frequencies set in the separation frequency setting step is about 4 times the number of data in the minimum unit transmitted per unit time of the modulated wave.
It is desirable to set the size to twice as large.

A computer-readable recording medium according to a fourth aspect of the present invention is a computer-readable recording medium that converts a modulated wave from a time component signal into a frequency component signal, and converts the modulated frequency component modulated wave into a carrier wave frequency. A computer-readable recording medium having recorded thereon a program for causing the computer to function as a means for detecting the frequency of the carrier to be detected from among frequency components predicted to include the frequency of the carrier to be detected. Means for setting a plurality of predicted frequencies to be set, means for setting a plurality of sets of two separated frequencies separated by the same value in directions larger and smaller than the set predicted frequencies, two sets of each set set Means for detecting a predicted frequency at which the amplitude values of the modulated waves of the frequency are substantially equal to each other; It is characterized in recording a program which means function as, for output as.

According to this configuration, the characteristic of the modulated wave of the frequency component, that is, the amplitude value of the modulated wave of two frequencies separated by the same value in the large direction and the small direction with the carrier frequency as the center is substantially equal to each other. Using the equality, the frequency of the carrier is determined. For this reason, even when the level of the carrier is lower than the level of data, noise, or the like, the frequency of the carrier can be easily obtained with high accuracy.

The means for detecting a predicted frequency such that the amplitude values of the modulated waves of the two separated frequencies in each set are substantially equal to each other may be obtained by modulating the two separated frequencies for each set. Means for multiplying the amplitude values of the waves with each other, means for adding the multiplication results of the amplitude values of the modulated waves of each pair of two separated frequencies for each set prediction frequency, and comparing the addition results for each prediction frequency. And a means for outputting the predicted frequency having the maximum addition result as the carrier frequency.

It is desirable that the predicted frequency is set in a range including a frequency at which the amplitude value of the upper first wave and the lower first wave of the modulated wave of the frequency component becomes substantially the maximum.

It is desirable that the maximum value of the difference between the two separation frequencies is set to about four times the number of the minimum unit data transmitted per unit time of the modulated wave.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The method of detecting a carrier frequency according to the embodiment of the present invention is a method of detecting a modulated wave modulated by a modulation method (for example, a frequency modulation method, a phase modulation method, or the like) in which a waveform of a frequency spectrum is symmetric with respect to the carrier. Two frequencies deviated by the same value in directions larger and smaller than the frequency of the carrier wave included in the modulated wave of the frequency component using the modulated wave of the frequency component obtained by converting the signal of the component to the signal of the frequency component Is a method of detecting a carrier frequency by utilizing the characteristic of a modulated wave of a frequency component that the amplitude values of the carrier waves are substantially equal. In other words, the modulated wave of the frequency component has a waveform substantially symmetrical in the horizontal axis direction about the carrier frequency, with the horizontal axis representing the frequency and the vertical axis representing the amplitude value. The carrier frequency detection method according to the embodiment of the present invention utilizes the above-described features, detects a frequency such that the waveform of the modulated wave of the frequency component is symmetric in the horizontal axis direction, and converts the detected frequency to the carrier frequency. This is the method of setting the frequency.

Hereinafter, a method for detecting the frequency of the carrier wave from the modulated wave of the frequency component will be described in detail.

First, from among the frequencies f1 to f2 (hereinafter referred to as capture ranges f1 to f2) of the frequencies that are predicted to include the carrier frequency to be detected, the symmetry of the modulated wave of the frequency component is determined. Frequency to be measured (hereinafter, center frequency f
0) is set, and the symmetry of the modulated wave is measured for the set center frequency f0. The measurement of the symmetry of the modulated wave
For the set center frequency f0, -2Fsym to + 2Fsym (Fs
ym: Performed within the range of symbol rate (the minimum number of data transmitted per unit time) (hereinafter, sample range).

Next, a method of measuring the symmetry of the modulated wave of the frequency component will be described. First, set center frequency f
The amplitude value Ap of the modulated wave corresponding to the frequency fp larger by the frequency fd is multiplied by the amplitude value Am of the modulated wave corresponding to the frequency fm smaller by the frequency fd. Next, the frequency
A process of changing the frequencies fp and fm by changing fd and multiplying the amplitudes Ap and Am of the modulated waves of the changed frequencies fp and fm by a plurality of processes within a range where the value of the frequency fd does not exceed 2Fsym Times, the amplitude value Ap of the modulated wave obtained for each process
And the result of multiplication of Am.

Next, the center frequency f0 is changed within the capture range, and the above-described processing is repeated for each center frequency F0 to obtain an addition result of the multiplication result of the amplitude values Ap and Am of the modulated wave. By comparing the addition result corresponding to the acquired center frequency f0,
The center frequency f0 at which the addition result becomes maximum is obtained, and the obtained center frequency is set as the carrier frequency to be detected. Since the waveform of the modulated wave is substantially symmetric about the center frequency F0 at which the addition result becomes the maximum, the carrier frequency can be detected by obtaining the center frequency f0 corresponding to the maximum value of the addition result. it can.

According to the above method, the carrier frequency can be detected even when the amplitude of the carrier is smaller than the level of the subcarrier, data, noise, or the like.

In order to detect the carrier frequency by the above method, the frequency at which the amplitude of the upper first wave of the modulated wave of the frequency component becomes the maximum and the frequency at which the amplitude of the lower first wave becomes the maximum are obtained. And are both required to be within the capture range.

Next, a carrier frequency detecting device for realizing the above carrier frequency detecting method will be described with reference to the drawings. As shown in FIG. 1, the carrier detection device includes an A / D converter 1, a quadrature detector 2, a buffer 3,
And a carrier frequency detector 4 for detecting a carrier frequency from a modulated wave supplied from the outside.

The A / D converter 1 samples a plurality of time-component modulated waves supplied from the outside at predetermined time intervals.
The sampled modulated wave of the time component is sequentially converted from analog to digital, and the converted digital signal is sequentially output to the quadrature detector 2. The quadrature detection unit 2 sequentially performs quadrature detection on the digital signals sequentially supplied from the A / D conversion unit 1, thereby forming a baseband in-phase component (I-phase signal I-phase signal I
(T)) and a quadrature component (Q-phase signal Q (t)),
The calculated I-phase signal I (t) and Q-phase signal Q (t) are output to the buffer 3 as a set of data. Buffer 3
The data supplied from the quadrature detector 2 is accumulated, and when the number of accumulated data reaches a predetermined number, the accumulated data is transferred to the carrier frequency detector 4.

As shown in FIG. 2, the carrier frequency detecting section 4 includes an FFT processing section 401, an amplitude calculating circuit 402, an amplitude value memory 403, a center frequency setting circuit 404, a sample frequency setting circuit 405, and a multiplication circuit. It comprises a circuit 406, an addition circuit 407, an addition result memory 408, a carrier frequency determination circuit 409, and a control circuit 410.

The FFT processing unit 401 is controlled by the control circuit 410 and performs fast Fourier transform on the time component data (a set of the I-phase signal I (t) and the Q-phase signal Q (t)) supplied from the buffer. Frequency component signal (in-phase component I (f)
And a quadrature component Q (f)), and outputs the conversion result to the amplitude calculation unit 402.

The amplitude calculating section 402 has an FFT processing section 401
(I (f) and Q)
The processing shown in Equation 1 is performed on the set of (f)), the amplitude value A (f) corresponding to each frequency is calculated, and the calculation result is supplied to the amplitude value memory 403.

[0035]

A (f) = (I (f) ² + Q (f) ² ) ^1/2

The amplitude value memory 403 includes an amplitude calculator 402
Is stored in association with the frequency.

The center frequency setting circuit 404 includes a controller 41
The frequency (center frequency f0 (m)) controlled to 0 and expected to be the carrier frequency is sequentially set. That is, as shown in FIG. 3A, the center frequency setting circuit 404 sets the frequency f1 to f2 (f1 <f2) in the acquisition range (the range expected to include the carrier frequency). The center frequency f0 (m) is sequentially set by sequentially updating the variable m of Equation 2 from 1 to r according to Equation 2. In addition, as shown in FIG. 3A, the capture range includes a frequency corresponding to the lower first peak of the modulated wave of the frequency component modulated wave and a frequency corresponding to the upper first peak of the modulated wave. Is set.

[0038]

F0 (m) = f1 + Δf * (m−1) where r is the number of center frequencies to be set (natural number of 1 or more) Δf: interval between center frequencies to be set

The sample frequency setting circuit 405 is controlled by the control circuit 410, and for each of the center frequencies f0 (m) set by the center frequency setting circuit 404, the center frequency f
0 (m), sample frequencies fm (k) and fp (k) (fm (k) <f
p (k)). The sample frequency setting circuit 405
Set the sample frequencies fm (k) and fp (k) to the center frequency f0
Update the variable k in Equation 3 from 1 to n in accordance with Equation 3 in the range of ± 2 Fsym (Fsym: the number of data of the minimum unit transmitted per unit time) around (m). Are set sequentially.

[0040]

Fp (k) = f0 (m) + k * 2Fsym / n (= f0
(M) + fs * k) fm (k) = f0 (m) -k * 2Fsym / n (= f0 (m) -f
s * k) where fs: interval of sample frequency n: number of samples / 2

For example, when setting the sample frequencies fp (k) and fm (k) with respect to the center frequency f0 (1), FIG.
As shown in (b), first, by setting the value k = 1 shown in Expression 3, the frequency fs is calculated from the center frequency f0 (1).
Large frequency fp (1) and low frequency fs (fm)
Set a pair with Next, by setting the value k in Equation 3 to k = 2, the frequency fp (2) larger by 2 * fs and the frequency fm smaller by 2 * fs than the center frequency f0 (1) are set.
A pair with (2) is set. Thereafter, similarly, the value k is updated to n, and a set of n sample frequencies fp and fm is set.

The multiplying circuit 406 is a center frequency setting circuit 4
The amplitude values Ap and Am of the modulated waves of the sample frequencies fp and fm set by the sample frequency setting circuit 405 are read from the amplitude value memory 403 for each of the center frequencies f0 (m) set by the step S04. Then, the read amplitude value Ap is multiplied by the amplitude value Am, and the multiplication result is supplied to the addition circuit 407. That is, the multiplication circuit 406 determines the set center frequency f
For 0 (m), for each variable k (for each set), the amplitude value Ap
(K) is multiplied by the amplitude value Am (k).

The adder circuit 407 calculates the center frequency f0 set by the center frequency setting circuit 404 according to equation (4).
In (m), the multiplication results supplied from the multiplication circuit 406 are sequentially added, and the addition result N is supplied to the memory 408.

[0044]

N = Ap (1) * Am (1) + Ap (2) * Am (2)
+ ... + Ap (n) * Am (n)

The addition result memory 408 stores the center frequency f0
The addition result N is stored in association with (m).

The carrier frequency detection circuit 409 is controlled by the control circuit 410, and the addition result N stored in the addition result memory 307 in association with the center frequency f0 (m).
Are sequentially read, and the center frequency f0 (m) when the addition result is the maximum (fx in the case of the waveform diagram shown in FIG. 3A) is output as the carrier frequency.

The control circuit 410 controls the entire operation of the carrier frequency detector 4 as described later.

Next, the operation of the carrier wave detecting device having the above configuration will be described.

First, the modulated wave is supplied from the outside to the A / D converter 1.
Is input to The A / D converter 1 samples a modulated wave of a time component supplied from the outside, converts the sampled modulated wave of the time component from analog to digital, and outputs the converted digital signal to the quadrature detector 2. The quadrature detector 2 performs quadrature detection on the digital signal output from the A / D converter 101, and outputs an in-phase component (I-phase signal I (t)) and a quadrature component (Q-phase) of the baseband of the digitized modulated wave. Signal Q (t)) and the generated I-phase signal I (t) and Q-phase signal Q (t) as a set of data in the buffer 3 sequentially.
To supply. The buffer 3 receives the supplied I-phase signal I
(T) and Q (t) are sequentially stored, and when the stored data reaches a predetermined number, the data is supplied to the carrier frequency detector 4.

Next, the operation of the carrier frequency detector 4 will be described with reference to the flowchart of FIG.

The control unit 410 of the carrier frequency detection unit 4
By controlling the FFT processing circuit 401 to perform a fast Fourier transform on data that is a set of the input I-phase signal I (t) and Q-phase signal Q (t) of the time component, the in-phase component in the frequency component ( I (f)) and the quadrature component (Q
(F)) is calculated (step S1).

The control section 410 controls the amplitude value calculation section 402 to perform the processing shown in the equation (5) similar to the above-mentioned equation (1) on the frequency component signals I (f) and Q (f). The amplitude value A (f) of the frequency modulated wave is calculated, and the calculation result is stored in association with the frequency (step S2).

[0053]

A (f) = (I (f) ² + Q (f) ² ) ^1/2

The control circuit 410 includes the center frequency setting circuit 4
04, and according to Equation 6 similar to Equation 2 described above, capture ranges f1 to f2 in which the carrier frequency is predicted to be included.
Within (f1 <f2), a frequency (center frequency f0 (m)) for measuring symmetry is set. First, the control circuit 410
Sets the variable m shown in Equation 6 to 1 (m = 1),
The minimum frequency f0 (1) (= f
1) is set (step S3).

[0055]

F0 (m) = f1 + Δf * (m−1) where r: number of center frequencies to be set (natural number of 1 or more) Δf: interval between center frequencies to be set

Subsequently, control section 410 controls sample frequency setting circuit 405 to set sample frequencies fp (1) and fm (1) corresponding to center frequency f0 (1). That is, in the processing shown in Equation 7 similar to Equation 3 above, Equation 7
Is set to 1 (k = 1) (step S4).

[0057]

Fp (k) = f0 (m) + k * 2Fsym / n (= f0
(M) + fs * k) fm (k) = f0 (m) -k * 2Fsym / n (= f0 (m) -f
s * k) where fs: interval of sample frequency n: number of samples / 2

The control circuit 410 calculates the amplitude value Ap (1) of the modulated wave at the sample frequency fp (1) and the amplitude value Am (1) of the modulated wave at the sample frequency fm (1) from the amplitude value calculating section 402. The read amplitude value Ap (1) and the read amplitude value Am (1) are multiplied by each other (step S5). The control circuit 410
The multiplication result is added to the previous multiplication result (0 when k = 1) (step S6), and the addition result is stored in association with the center frequency.

The control circuit 410 determines that the value of the variable k in Equation 7 is n
It is determined whether or not (the number of samples / 2) has been achieved (step S7). If it is determined that the value of the variable k has not reached n, the variable k is updated (step S10), and the updated variable k Perform the processing of the above-described steps S5 and S6.

If the control circuit 410 determines in step S7 that the value of the variable k has reached n, it then determines whether or not the variable m in equation 6 has reached r (the set number of center frequencies). (Step S8).

If the control circuit 410 determines that the value of the variable m has not reached r, it updates the variable m (step S).
11), the center frequency f corresponding to the updated new variable m
For 0 (m), the processing from step S4 to step 7 described above is performed. On the other hand, when it is determined that the value of the variable m has reached r, the value of the addition result stored in association with the center frequency f0 (m) is compared, and the center value at which the value of the addition result becomes the maximum value is determined. The frequency is obtained, and the obtained center frequency is output as the carrier frequency (step S9), and the carrier frequency detection processing ends.

As described above, according to the carrier frequency detecting method according to the embodiment of the present invention, the characteristics of the modulated wave of the frequency component (the waveform of the modulated wave is symmetrical with respect to the carrier frequency). ) Is used to detect the frequency of the carrier. Therefore, the maximum level (amplitude value) of the carrier to be detected is the level of data or noise (amplitude value).
Even if it is lower, the carrier can be detected easily and with high accuracy.

It should be noted that the present invention is applicable to any of the above-described embodiments if the carrier is detected by utilizing the characteristic of the modulated wave of the frequency component that the waveform of the modulated wave of the frequency component is targeted around the frequency of the carrier. Not limited to the form, arbitrarily change
It is possible to apply. For example, the operation of the carrier detection unit 4 shown in FIG. 4 may be realized by software.
In this case, the entire operation of the carrier wave detector 4 shown in FIG. 4 may be realized by software, or only a part of the operation of the carrier wave detector 4 may be realized by software. In addition, the configuration of the carrier frequency detector 4 shown in FIG. 2 can be arbitrarily changed.

It should be noted that the present invention provides that if the waveform of the supplied modulated wave (frequency component signal) is substantially symmetrical in the large and small directions around the carrier frequency,
The present invention can be applied to detection of a carrier frequency of an arbitrary modulated wave.

By increasing the frequency range for measuring the modulated wave, the proportion of the band power value is increased. Therefore, by widening the measurement frequency range of the modulated wave, the detection accuracy of the carrier frequency can be improved.

[0066]

As described above, according to the carrier frequency detection circuit, the detection method, and the recording medium of the present invention, the carrier wave of the frequency component modulated wave converted from the time component signal to the frequency component signal is used. The frequency of the carrier wave is detected by using the characteristic of the modulated wave of the frequency component that the amplitude values of the modulated waves of the two separated frequencies that are separated by the same value in the directions larger and smaller than the frequency are substantially equal. Therefore, even when the maximum level (amplitude value) of the carrier to be detected is lower than the level (amplitude value) of data or noise, the carrier can be detected easily and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a carrier frequency detection device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a carrier frequency detection unit shown in FIG.

FIG. 3 is a diagram for explaining a method of setting a center frequency set by a center frequency setting circuit and a method of setting a sample frequency set by a sample frequency setting circuit.

FIG. 4 is a flowchart for explaining the operation of the carrier frequency detector of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 A / D conversion unit 2 Quadrature detection unit 3 Buffer 4 Carrier frequency detection unit 401 FFT processing unit 402 Amplitude value calculation unit 403 Amplitude value memory 404 Center frequency setting circuit 405 Sample frequency setting circuit 406 Multiplication circuit 407 Addition circuit 408 Addition result memory 409 Carrier frequency determination circuit 410 Control circuit

Claims (14)

[Claims] 1. A carrier frequency detecting circuit for converting a modulated wave from a time component signal to a frequency component signal, and detecting a carrier frequency from the converted frequency component modulated wave, including a carrier frequency to be detected. From among the predicted frequency components, predicted frequency setting means for setting a plurality of predicted frequencies predicted to be carrier frequencies, in each of a direction larger and smaller than the predicted frequency set by the predicted frequency setting means Separation frequency setting means for setting a plurality of sets of two separation frequencies separated by the same value, and the amplitude values of the modulated waves of the two separation frequencies of each set set by the separation frequency setting means are substantially equal to each other. Prediction frequency detection means for detecting a prediction frequency such that the prediction frequency detected by the prediction frequency detection means should be detected. The frequency of the carrier, the detection circuit of carrier frequency, characterized in that. 2. The method according to claim 2, wherein the predicted frequency detecting means comprises:
A multiplying means for multiplying the amplitude values of the modulated waves of the two separated frequencies by each other; and a set of two sets each set by the separated frequency setting means for each of the predicted frequencies set by the predicted frequency setting means.
An adding means for adding the multiplication results of the amplitude values of the modulated waves of the two separated frequencies; and a carrier frequency for comparing the addition results added by the adding means and outputting a predicted frequency having the maximum addition result as a carrier frequency. The carrier frequency detecting circuit according to claim 1, further comprising: determining means. 3. The predictive frequency setting means sets a predictive frequency in a range including a frequency having substantially the maximum amplitude value of an upper first wave and a lower first wave of a modulated wave of a frequency component. 3. The carrier frequency detecting circuit according to claim 1, wherein 4. The maximum value of the difference between the two separation frequencies set by the separation frequency setting means is set to about four times the number of minimum unit data transmitted per unit time of the modulated wave. The carrier frequency detection circuit according to any one of claims 1 to 3, wherein: 5. A receiving means for receiving a modulated wave, a means for detecting the modulated wave received by the receiving means to determine an in-phase component and a quadrature component of a baseband, and Means for converting a signal from a signal in the time domain into a signal of an in-phase component and a quadrature component in the frequency domain, and a square root of a sum of a square of the signal of the in-phase component in the frequency domain and a square of the signal of the quadrature component in the frequency domain. 5. The carrier frequency detection circuit according to claim 1, further comprising: a means for obtaining the frequency component and modulating the frequency component with the frequency component. 6. A carrier frequency detecting circuit for detecting a frequency of a carrier of a signal including a carrier, wherein a plurality of predicted frequencies predicted to be carrier frequencies are set, and for each of the set predicted frequencies, the predicted frequency is calculated. Separation frequency setting means for setting a set of two separation frequencies separated by the same value in each of the larger direction and the smaller direction, and at the separation frequency set by the separation frequency setting means, determine the amplitude of the signal, A carrier frequency detecting means for setting a predicted frequency at which the amplitude of the signal at the set separation frequency becomes substantially equal to a carrier frequency, the carrier frequency detecting circuit comprising: 7. A method for converting a modulated wave from a signal of a time component to a signal of a frequency component, and detecting a frequency of a carrier from the converted modulated wave of the frequency component. Among the frequency components to be set, a prediction frequency setting step of setting a plurality of prediction frequencies predicted to be the frequencies of the carrier waves, the same in each of a direction larger and smaller than the prediction frequency set in the prediction frequency setting step A separation frequency setting step of setting a plurality of sets of two separation frequencies separated by a value, and an amplitude value of a modulated wave of the two separation frequencies of each set set in the separation frequency setting step becomes substantially equal. A predicted frequency detecting step of detecting a predicted frequency, comprising: a predicted frequency detected in the predicted frequency detecting step. The frequency to be detected carrier, the detection method of a carrier frequency, characterized in that. 8. The predictive frequency detecting step includes: a multiplying step of multiplying the amplitude values of modulated waves of two separated frequencies by each set set in the separated frequency setting step; For each predicted frequency, an addition step of adding the multiplication result of the amplitude values of the modulated waves of the two separated frequencies of each set set in the separation frequency setting step, and comparing the addition result added in the addition step, The carrier frequency detecting method according to claim 7, further comprising: a carrier frequency determining step of outputting a predicted frequency having the maximum addition result as a carrier frequency. 9. The predicted frequency set in the predicted frequency setting step includes a frequency including substantially the maximum amplitude value of the upper first wave and the lower first wave of the modulated wave of the frequency component. 8. The method according to claim 7, wherein:
Or the method of detecting a carrier frequency according to 8. 10. The maximum value of the difference between the two separation frequencies set in the separation frequency setting step is set to about four times the number of the minimum unit data transmitted per unit time of the modulated wave. 9. The method according to claim 7, wherein
10. The method of detecting a carrier frequency according to any one of claims 9 to 9. 11. A computer-readable program recording a program for causing a computer to function as a means for converting a modulated wave from a time component signal to a frequency component signal and detecting a carrier frequency from the converted frequency component modulated wave. Means for setting a plurality of predicted frequencies predicted to be the carrier frequency from among frequency components predicted to include the frequency of the carrier to be detected, the set predicted frequency Means for setting a plurality of sets of two separated frequencies separated by the same value in each of the larger direction and the smaller direction, such that the amplitude values of the modulated waves of the set two separated frequencies are substantially equal to each other A program for functioning as a means for detecting the predicted frequency, a means for outputting the detected predicted frequency as a carrier frequency, and Computer readable recording medium. 12. A means for detecting a predicted frequency such that the amplitude values of the modulated waves of the two separated frequencies of each set set are substantially equal to each other, comprising: Means for multiplying the amplitude values of the modulated waves by each other, means for adding the result of multiplication of the amplitude values of the modulated waves of each pair of two separated frequencies for each set prediction frequency, and adding the addition result for each prediction frequency 12. The computer-readable recording medium according to claim 11, further comprising: means for outputting, as a carrier frequency, a predicted frequency having a maximum result of the addition. 13. The prediction frequency is set in a range including a frequency having substantially the maximum amplitude value of the first upper wave and the lower first wave of the modulated wave of the frequency component. The computer-readable recording medium according to claim 11, wherein: 14. The maximum value of the difference between the two separated frequencies is set to be about four times as large as the number of minimum unit data transmitted per unit time of the modulated wave. 14. The computer-readable recording medium according to claim 11.